1. Field of the Invention
The present invention relates to an improvement of a socket for high density terminals utilized when an electronic component (e.g., a land grid array type LSI package) in which an integrated circuit is built, is mounted on a wiring board, a method of mounting the electronic component using the socket for high density terminals and an electronic component adjusting unit.
2. Description of Related Art
The number of signal pins is expected to be increased to enable an integrated circuit such as a processor of a computer to process huge information at high speed in short time. Further, since densification also progresses, a pitch between signal pins tends to be narrowed. As an example of an electronic component the densification of which progresses, there is a land grid array type LSI package (hereinafter merely called “LGA”). The LGA is not directly soldered on a wiring board. The LGA is mounted on the wiring board utilizing a socket for high density terminal pins. The socket is called an “LGA socket”. The LGA socket is used for enabling easy attachment and detachment of the LGA to/from the wiring board. The LGA socket is attached to an inspection equipment and a computer, so as to attach the LGA to the inspection equipment utilized for inspecting LGA, or so as to attach and detach a replaceable computer card.
FIG. 11 shows an example of mounting the LGA using a general LGA socket. The LGA socket 101 includes a concave space 103 for inserting an LGA 102. The LGA socket 101 includes plural pins 106 individually contacting each of plural terminals 105 arranged on one surface of the LGA 102. The pins 106 are installed on the bottom 104 of the concave space 103. Each of the pin 106 includes a sleeve 107 and a needle 108. Each needle 108 is independently forced toward the LGA 102 by a spring installed inside the sleeve 107. A contact 109 protruded downward from the sleeve 107 on the side of a board of the LGA socket 101 pierces a lower surface of the socket 101 and is exposed outside, and contacts a terminal 111 of the wiring board 110. Internal wiring 112 is provided to the wiring board 110, and the terminal 111 is connected to the internal wiring 112.
A positioning pin 113 is installed on the lower surface of the LGA socket 101. The position of the LGA socket 101 to the wiring board 110 is adjusted by inserting the positioning pin 113 into a positioning hole 114 on the side of the wiring board 110.
For inserting the LGA 102 into the wiring board 110, first, the positioning pin 113 is inserted into the positioning hole 114, the contact 109 is precisely positioned on the terminal 111 of the wiring board 110, and the LGA socket 101 is fixed to the wiring board 110.
Next, the LGA 102 is inserted into the concave space 103, and the terminal 105 of the LGA 102 and an end of the pin 106 are contacted with each other by pressing the LGA 102 toward the bottom 104 of the concave space 103 with a load Q1 as shown in FIG. 12, so as to conduct electricity between the pins 106 and the terminals 105. The terminal 111 of the wiring board 110 and the contact 109 on the side of the board of the LGA socket 101 are contacted so as to conduct electricity between the terminal 111 and the contact 109. The LGA 102 is fixed to the concave space 103 by pressing by the load Q1. The positioning pin 113 is fixed to the positioning hole 114, and the LGA socket 101 is fixed to the wiring board 110.
The needles 108 urged toward the electronic component by the spring installed inside the sleeve 107, contact the terminals 105, and then retract inside the sleeves 107 against the force of the spring. Since the needles 108 retract inside the sleeve 107, an overlapped part of an inner surface of the sleeve 107 and a peripheral surface of the needle 108 is increased. In other words, an area that the needles 108 and the sleeves 107 electrically contact with each other is increased. Further, since the needles 108 are pressed toward the terminals 105 by the force caused by compressing the spring, electricity can be securely conducted between the needle 108 and the terminal 105.
However, when the number of the terminals 105 of the LGA 102 increases, a pitch between the terminals 105 is necessarily narrowed, and the area of the terminal 105 is also reduced. Normally, a discrepancy for the wiring pitch may not be caused. However, due to a dimensional deviation, a discrepancy for the position of the terminals 105 may occur. In such a case, the LGA socket 101 which adjusts the position of the terminals 105 with respect to the pins 106 based on a size of the LGA socket 101 and a size of the electronic component 102 may cause a problem regarding the discrepancy of the position of the terminals 105 with respect to the pins 106.
FIG. 13 shows a case of a large discrepancy of the position of the terminals 105 with respect to the pins 106. When the terminals 105 are displaced with respect to the pins 106 in a direction substantially parallel to the LGA 102 as shown in FIG. 13, the end of the pin 106 and the terminal 105 of the LGA 102 are not matched when the LGA 102 is inserted into the LGA socket 101. In this case, even if the LGA 102 is pressed toward the pins 106 with the load Q1 as shown in FIG. 14, normal conduction may not occur. The discrepancy of the position of the terminals 105 with respect to the pins 106 may be caused in not only in a direction corresponding to a width direction of the LGA 102, but also in a direction corresponding to a depth direction of the LGA 102.
The discrepancy of the position of the terminals 105 with respect to the pins 106 may be solved by increasing an accuracy of manufacturing the LGA 102. However, increasing the accuracy of manufacturing causes an increase in cost of the LGA 102.
Therefore, an LGA socket that enables reliable conduction even if there is a discrepancy of the position of the terminals 105 with respect to the pins 106 is needed.
A related art (patent document 1) adjusts a position of terminals by inserting plural positioning pins 116 provided on an terminal surface 115 of LGA 102 into each hole 118 on the side of a socket 117 (FIGS. 15(a) and 15(b)). The positioning pin 116 is required to be attached to the terminal surface 115 of the LGA 102, and the cost may be increased.
In a patent document 2, a system includes a small-sized camera 120 buried in a socket for inspection 119. An external terminal of a semiconductor device 121 is photographed by the small-sized camera 120. A result of recognizing the image is displayed on an output device 123 after the image is recognized by an image recognizing device 122, and the semiconductor device 121 is displaced to a desired position of the socket for inspection 119 by operating a cross slide 124 (FIG. 16). High precision is required for this system, however. Further, the small-sized camera 120, required to be arranged for every the socket for inspection 119, is a high-priced inspection equipment. Therefore, it is difficult to apply this system to a purpose except inspection, for example, a wiring board on which the semiconductor device 121 is mounted.
[Patent document 1] JP-A-2003-078059
[Patent document 2] JP-A-2006-023166